Arsine is known to be extremely toxic to humans, much more toxic than arsenic oxide which is commonly used as a rat poison.
In spite of its toxicity, arsine is widely used in the semi-conductor industry as an arsenic source for the fabrication of semi-conductors (such as gallium-arsenide wafers) and as a gas dopant for silicon devices using CVD-reactors and diffusion ovens, molecular beam epitaxy depositors or ion implanters.
Typically, arsine is conventionally supplied for these commercial applications by means of cylinders containing either pure arsine or arsine in admixture with a carrier gas such as hydrogen or helium. Leaks of these arsine-containing cylinders are potentially very hazardous, particularly during transportation and shipment of these cylinders when back-up scrubbing or other safety systems may not be in place. Under these circumstances, venting or rupture of the cylinder is potentially catastrophic.
The use of zeolites to scrub waste gases for the removal of toxic and/or corrosive materials in the waste gas is known. By way of illustration, Canadian Pat. No. 1,116,537, assigned to Hoechst A.-G., discloses a process for recovering phosphine from a waste gas mixture also containing hydrogen, nitrogen, and/or non-polar lower hydrocarbons by contacting the waste gas with a zeolite to adsorb the phosphine. The zeolite is subsequently heated to desorb and recover the phosphine. This Canadian patent does not disclose or suggest the use of zeolites to recover arsine from waste gas. In view of differing physical and chemical properties of phosphine and arsine (e.g., arsine is much more labile), any prediction of the effect of zeolites on arsine in waste gas (to say nothing of non-waste gas) would be the subject of mere speculation based upon a reading of the Canadian patent.
In view of the above, new systems that provide improved, relatively safe, storage of arsine in a non-waste (feed) gas, together with delivery of the arsine as needed would be highly desired, particularly in the electronics industry.